Cast aluminum cold plates having a plurality of individual fluid conveying tubes joined into coil packs or tubing bundles that are encased in the cold plate and extend along serpentine paths are often used to provide heat exchange cooling of liquids flowed through the tubes. Such cold plates have particular application in the beverage dispense equipment industry for chilling beverage liquids such as concentrate beverage syrups and diluents for the syrups, which diluents typically consist of carbonated and non-carbonated or plain water that are mixed with the syrups at post-mix beverage dispensing valves t dispense cold drinks. In such an application, ice is placed on and in heat exchange contact with a top surface of a cold plate to provide for heat exchange cooling of beverage liquids as they flow through the serpentine coils of tubing encased in the cold plate. Cold plates are manufactured by pouring molten aluminum into a mold in which is first placed the fluid conveying tubes arranged in desired configurations. After cooling and hardening of the aluminum, the coil bundle is encased in the aluminum and the resulting cold plate is prepped and finished for placement into a beverage dispensing machine. In particular, the ice contacting and retaining surface of the cold plate is milled to produce a smooth finish on the surface in order to enhance heat exchange efficiency.
The molten aluminum poured into the cast is quite hot and to prevent warping and distortion of the coil pack or tubing bundle as it is heated during the casting process it is necessary that the coil pack, typically consisting of stainless steel tubing, be strapped together using metal wires that also are usually of stainless steel, in order that the coil pack be made to retain a desired configuration during the casting process. Without such restraint, movement of the coil pack as a result of the heat from the molten aluminum can warp and distort the coil pack to an undesired geometry, and excessive movement of the tubing can interfere with and prevent attaining a desired spacing of the tubing within the cold plate and from the outer surfaces of the cold plate. Such interference is of particular concern with respect to the top surface of the cold plate on which ice resides. If there is too little distance of the tubing from the top surface, tubing could show through the surface and be subject to mechanical damage relating to post casting surface finishing or from damage occurring when the cold plate is used in a beverage dispenser. If the is too great a distance between the tubing and the top surface, cooling performance will be negatively impacted.
To obtain optimum and consistent cooling performance it is therefore desired to control and maintain the position of the coil bundles within and from surfaces of the cast aluminum. To this end, portions of the wire restraints can be bent outward to comprise spacers or standoffs that extend from the coil bundle and contact the inner surfaces of the cold plate mold. The standoffs then define a desired spacing between the exterior surface of the cold plate and the coil bundle. A problem with this approach concerns the subsequent milling of the ice retaining cold plate top surface, since in cutting through the excess aluminum the milling equipment is also required to cut through the stainless steel standoffs, which dulls and wears out the cutting wheels of the milling equipment much more quickly than if they were to encounter only aluminum. As a result, the cost of the post casting finishing or milling process is greatly increased. Also, the stainless steel wire standoffs provided by the wire restraints have a lower coefficient of heat conduction than does aluminum, which detracts from the cooling performance of the cold plate.
Accordingly, it would be very desirable to have a tubing bundle standoff for use in the fabrication of cold plates that reduces or eliminate problems encountered with use of stainless steel wire standoffs.